Has anyone tried a Favored Soul/Sorcerer Mystic Theurge build?

[Glyfair]

I think the easiest solution is the Favored Soul/Sorcerer with the Education feat (in the Eberron campaign setting, both Forgotten Realms books, as well as Ghostwalk). While they are far behind in spell power, they do have the advantage of sharing the prime requisite. He still needs Wisdom for its favored soul spell DCs, but that's not too bad.